Adobe is working on a fix for a Flash Player vulnerability that can be exploited via clickjacking techniques to turn on people's webcams or microphones without their knowledge.

The issue was discovered by a Stanford University computer science student named Feross Aboukhadijeh who based his proof-of-concept exploit on a similar one disclosed back in 2008 by an anonymous researcher.

Technically known as user interface (UI) redressing, clickjacking is a type of attack that combines legitimate Web programming features, like CSS opacity and positioning, with social engineering to trick users into initiating unwanted actions.

For example, clickjacking techniques have been used to trick Facebook users into liking rogue pages or posting spam on their walls by making Like and Share buttons transparent and superimposing them over legitimate-looking ones.

The 2008 webcam spying attack involved loading the Adobe Flash Player Settings Manager, which is actually a page hosted on Adobe's website, in an invisible iframe and tricking users into enabling webcam and microphone access through it.

The lure used by the exploit was a JavaScript game that required users to click various innocent-looking buttons on the screen. Some of the clicks were part of the game, while others were redirected to the invisible iframe.

Adobe responded at the time by inserting code into the Flash Player Settings Manager page that prevents it from being iframed. However, Aboukhadijeh realized that the settings manager is actually an SWF (Shockwave Flash) file and that loading it directly into an iframe, instead of the entire page, would bypass Adobe's frame-busting code.

In essence this is the same 2008 vulnerability exploited through a slightly different attack vector. "I was really surprised to find out that this actually works," Aboukhadijeh said.

He said that he emailed Adobe about the problem a few weeks ago, but got no response. However, the company contacted him after the public disclosure to inform him that they are working on a fix which will be deployed on their end and won't require users to update their Flash Player installations.

Using an SWF file hosted on Adobe's servers to modify Flash Player settings instead of a local interface is something that has generated problems before. For example, privacy advocates have complained in the past that this makes clearing Local Shared Objects (LSOs), commonly known as Flash cookies, difficult and confusing.